1. Field of the Invention
The present invention relates to used toner recovering means in electrostatic recording apparatus, such as electrophotographic copying machines, and more particularly to transport means for directing the remaining toner from a cleaning device to a transport member which carries the toner to a developing device.
2. Description of the Prior Art
Residual toner from the surface of an image forming member of an electrostatic recording apparatus, such as an electrophotographic copying machine, has generally been disposed of by replacing the web used for cleaning the toner remaining on the image forming area after completion of image formation, or by discarding the used toner deposited in a cleaning device after a definite period of copying operations. However, the performance of such laborious maintenance practices at regular or irregular intervals is expensive at least insofar as the employee time involved. In addition, with the relatively recent advent of high-speed copiers, increases in the number of copying sheets used correspondingly increases the discharged volume of used toner, leading to demands that the toner collected and deposited by the cleaning means be automatically recovered and returned to the developing device.
To meet such demands, new recovery means have been proposed such, for example, as those disclosed in Japanese Patent Publication Open to Public Inspection (hereinafter referred to as Japanese Pat. O.P.I. Publication) No. 45933/1972 wherein an endless bead chain circulates between the cleaning means and the toner replenishing means; Japanese Pat. O.P.I. Publication No. 71649/1973 utilizing a screw conveyor; Japanese Pat. O.P.I. Publication No. 3636/1975 providing a rotary means rotatable coaxially with a photosensitive drum; U.S. Pat. No. 3,333,572 and No. 3,405,682 incorporating a belt conveyor; and the like.
However, toner recovered by the cleaning means, irrespective of the manner in which it is transported, must be transported along the surface of the photosensitive body to either one or both ends thereof in order to place the recovered toner on the transport means provided at the end of the photosensitive body. And having reached one end of the photosensitive body--even in the above-described known art--return of the toner to the development section by the shortest possible route necessitates that the transport direction be changed perpendicular to the direction in which the toner has been carried to reach the end of the photosensitive body.
In this change of transport direction, a number of problems have arisen--for example, the toner, because it is formed of very minute particles, tends to form lumps during its transport along the surface of the photosensitive body; because it is in powder form, the toner tends to scatter and leak through small gaps within the apparatus, staining the interior thereof; when the toner, at the point of transport direction change, does not successfully ride in the subsequent transport means, it is prone to becoming mixed with deteriorated toner produced by friction between toner particles; and, in the worst case, unsatisfactory transportation produces an excessive accumulation of toner in the chamber of the cleaning means which can thereby become ineffective in its cleaning function, thus leading to possible malfunction in the recycling of toner.